SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-32040

It may be possible to have an extremely long aggregation pipeline in conjunction with a specific stage/operator and cause a stack overflow due to the size of the stack frames used by that stage.

HIGH 7.5EPSS 2.01%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.01%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

It may be possible to have an extremely long aggregation pipeline in conjunction with a specific stage/operator and cause a stack overflow due to the size of the stack frames used by that stage. If an attacker could cause such an aggregation to occur, they could maliciously crash MongoDB in a DoS attack. This vulnerability affects MongoDB Server v4.4 versions prior to and including 4.4.28, MongoDB Server v5.0 versions prior to 5.0.4 and MongoDB Server v4.2 versions prior to 4.2.16. Workaround: >= v4.2.16 users and all v4.4 users can add the --setParameter internalPipelineLengthLimit=50 instead of the default 1000 to mongod at startup to prevent a crash.

CVSS 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
2.01% probability · 81th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-121, CWE-787
Affected
mongodb/mongodb
Source
cna@mongodb.com
EPSS trend
0%3%5%27 October 2026: 2.01%27 October 202627 October 2026

EPSS 2.0% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.